The present invention relates to an authenticity identifying film and authenticity identifying system for preventing the forgery of articles including cards, gift certificates, currency notes, tickets, bank notes, securities, betting tickets and the like, and a method of using the authenticity identification film.
A conventional method of preventing the forgery of credit cards, deeds, currency notes and the like attaches an authenticity identifying medium which is difficult to forge to an article to be protected from forgery, and identifies the authenticity identifying medium visually or mechanically. A hologram or a liquid crystal film is used as the authenticity identifying medium.
Holograms include those carrying a holographic image of characters and patterns for visual identification, those carrying a holographic image of numerical codes and special patterns for mechanical recognition, and those carrying both the foregoing holographic images. The hologram has been prevalently used because the hologram cannot be copied by an ordinary color copying machine or the like and is effective in forgery prevention, the hologram is attractive because of its highly aesthetic design, the hologram is difficult to produce and hence the hologram has been prevalently used.
Previously proposed methods employing liquid crystal films includes a method proposed in JP-A No. Sho 63-51193 using a cholesteric liquid crystal which looks in different colors when seen from different directions, and a method proposed in JP-A No. Hei 8-43804 using an optically anisotropic nematic liquid crystal. The method using a cholesteric liquid crystal is able to record two characteristics of the cholesteric liquid crystal, namely, selective reflectivity and circular polarization selectivity, as information for authenticity identification on a single medium, mass-production of a cholesteric liquid crystal of fixed properties is difficult and hence this method is excellent in forgery preventing effect.
However, recently prevalent hologram producing techniques have made possible the production of counterfeits of conventional holograms, which reduced the forgery preventing effect of the conventional holograms.
Although the forging of liquid crystal films is difficult, the mass production of authentic liquid crystal films also is difficult, and hence liquid crystal films have not been prevalently used as authenticity identification mediums.
It is an object of the present invention to provide an authenticity identifying film having a highly esthetic design, difficult to forge and facilitating either visual or mechanical authenticity identification, an authenticity identifying system and a method of using the authenticity identifying film.
An authenticity identifying film according to the present invention includes a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, wherein the reflective film is provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image.
An authenticity identifying film according to the present invention includes a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer laminated to the reflective film having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image.
The authenticity identifying film according to the present invention is characterized in that the reflective film is a liquid crystal film.
The authenticity identifying film according to the present invention is characterized in that the reflective film has a fixed cholesteric phase.
The authenticity identifying film according to the present invention is characterized in that the hologram forming part includes an embossed hologram.
The authenticity identifying film according to the present invention may further include an adhesive layer to be attached to an article.
The authenticity identifying film according to the present invention is characterized in that the reflective film is delaminated when the authenticity identifying film is separated from an article.
The authenticity identifying film according to the present invention may further include a protective film covering a surface of the reflective film opposite a surface of the same facing an article.
The authenticity identifying film according to the present invention may further include a base film attached by an additional adhesive layer to a surface of the reflective film opposite a surface of the same facing an article.
The authenticity identifying film according to the present invention may further include a light absorbing layer interposed between the reflective film and the adhesive layer.
An article with an authenticity identifying film according to the present invention comprises: an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, the reflective film being provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image, or an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer laminated to the reflective film, having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image; an article to which the authenticity identifying film is bonded; and a photograph interposed between the article and the authenticity identifying film.
An authenticity identifying system according to the present invention comprises: an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, the reflective film being provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image, or an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer laminated to the reflective film, having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image; a light source unit that irradiates the authenticity identifying film with light; and a detecting unit for detecting reflected light from the authenticity identifying film and the holographic image.
In the authenticity identifying system according to the present invention, the detecting unit is capable of detecting only light in a predetermined waveband.
In the authenticity identifying system according to the present invention, the detecting unit is capable of measuring the intensity of transmitted light.
In the authenticity identifying system according to the present invention, at least either the light source unit or the detecting unit is provided with a polarizing plate, a phase plate or a band-pass filter.
According to the present invention, a method of using an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, the reflective film being provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image, or an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light or left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer laminated to the reflective film, having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image, the method comprising the steps of: irradiating the authenticity identifying film with right-handed circularly polarized light or left-handed circularly polarized light; and deciding that the authenticity identifying film is authentic when either of right-handed circularly polarized light and left-handed circularly polarized light can be detected and the other circularly polarized light cannot be detected.
According to the present invention, a method of using an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light and left-handed circularly polarized light of at least incident light to produce reflected light, the reflective film being provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image, or an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light and left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer laminated to the reflective film, having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image, the method comprising the steps of: irradiating the authenticity identifying film with light including right-handed circularly polarized light and left-handed circularly polarized light; and deciding that the authenticity identifying film is authentic when the holographic image from the authenticity identifying film can be read from the authenticity identifying film in a direction different from that of the reflected light.
According to the present invention, a method of using an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light and left-handed circularly polarized light of at least incident light to produce reflected light, the reflective film being provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image, or an authenticity identifying film including a reflective film laminated to the reflective film, having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light and left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image and laminated to the reflective film, the method comprising the steps of: irradiating the authenticity identifying film with light including right-handed circularly polarized light and left-handed circularly polarized light; and deciding that the authenticity identifying film is authentic when the film has a part that cannot be visually recognized when the authenticity identifying film is observed visually through an examining tool that transmits only either of right-handed circularly polarized light and left-handed circularly polarized light.
According to the present invention, a method of using an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light and left-handed circularly polarized light of at least incident light to produce reflected light, the reflective film being provided with a hologram forming part that reflects circularly polarized light of the same circular polarization as that of the reflected light in a direction different from that of the reflected light to form a holographic image, or an authenticity identifying film including a reflective film having a circularly polarized light selectivity to reflect only either of right-handed circularly polarized light and left-handed circularly polarized light of at least incident light to produce reflected light, and a hologram forming layer laminated to the reflecting film, having a hologram forming part that reflects circularly polarized light of circular polarization opposite that of the reflected light in a direction different from that of the reflected light to form a holographic image, the method comprising the steps of: irradiating the authenticity identifying film with light including right-handed circularly polarized light and left-handed circularly polarized light; and measuring the light intensity difference between the intensities of right-handed circularly polarized light and that of the intensity of left-handed circularly polarized light transmitted by an examining tool that transmits only either of right-handed circularly polarized light and left-handed circularly polarized light and deciding whether or not the authenticity identifying film is authentic on the basis of the light intensity difference.